Elastic_load_balancers

New

Use the New action button to create a new Amazon Elastic Load Balancer. The ability to create and use ELBs is automatically supported, however additional charges do apply. See Amazon for current pricing information.

Field descriptions are:

• Name - The name of our Elastic Load Balancer. The name cannot contain any spaces and must use either dashes or alpha and numeric characters.
• Deployment - Specify a deployment to associate with your Elastic Load Balancer. The ELB will be visible at the bottom at the deployment???s servers tab. This field is optional, but recommended. Note: An ELB will not be included in usage reports and will not be included when a Deployment is cloned.
• Availability Zones - A checkbox list of the availability zones your load balancer will service. An ELB will load balance across instances in the selected availability zones within a region. An ELB cannot load balance across different EC2 regions.
• Listeners - Specify the load balancer port, instance port and protocol. This takes the following format: Protocol:LoadBalancerPort->InstancePort
  • Protocol - Routing transport protocol. HTTP or TCP.
  • LoadBalancerPort - External port of the load balancer. Valid ports are 80, 443, 1024-65535.
  • InstancePort - TCP port on which the Server on the Instance is listening. Valid ports are 1 to 65535.
• Description - Describe the use/function for your load balancer.

Index

Amazon's Elastic Load Balancing (ELB) distributes incoming traffic requests amongst multiple server instances. Servers can be located in multiple availability zones. As a best practice for mission critical applications, configuring your Elastic Load Balancer to service more than one zone is recommended. Amazon does not appear to use a traditional round-robin logic where requests are evenly distributed across all application servers. Amazon promises to send new requests to the least loaded server. Therefore, you may notice unpredictable traffic patterns across your application tier.

If you have valid Amazon Web Services (AWS) EC2 credentials, you are automatically granted the Elastic Load Balancer service. No additional service sign-ups are required, however additional charges do apply. See Amazon for current pricing information.

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Show

One of the more common edits you can perform from the Dashboard is changing (adding to or deleting from) the Availability Zones in which your load balancer distributes traffic.

Info tab

View general information about the ELB.

• Description - Describe the use/function of the elastic load balancer.
• DNS name - The DNS name for the LoadBalancer.
• Listeners - The external TCP port of the LoadBalancer.
• Created at - The timestamp of when the ELB was created.
• Target - The external TCP port of the ELB.
• Interval - The approximate interval (in seconds) between health checks of an individual instance. (Valid Range: 5-600) Default is 30 seconds. Interval value must be greater than the Timeout value of the healthcheck.
• Timeout - The amount of time (in seconds) during which no response means a failed health probe. (Valid Range: 2-60) Default is 5 seconds. Interval value must be less than the Interval value of the healthcheck.
• Healthy threshold - The number of consecutive health probe successes that must occur in order for an instance to move back to a "Healthy" state. (Valid Range: 2-10) Default is 3.
• Unhealthy threshold - The number of consecutive health probe failures that must occur in order for an instance to be considered in an "Unhealthy" state. (Valid Range: 2-10) Default is 10.
• Availability zones - The serviceable availability zones. The ELB will distribute traffic to instances across all selected availability zones.

Listeners tab

The Listeners tab allows you to specify the protocol and ports that the Elastic Load Balancer (ELB) will use to send/receive traffic. When you first create a new ELB, it's automatically set up with one listener already predefined. By default, an ELB will be configured to listen over HTTP on port 80 and forward traffic to port 80 on the receiving EC2 instances, which are typically your application servers. (HTTP; 80->80)

For SSL communications, select the 'HTTPS' protocol and select a Security Certificate.

• Protocol - The routing transport protocol that will be used by the ELB. (TCP, HTTP, HTTPS)
• Load balancer port - External port that the ELB will listen on to accept client requests. Valid ports are 80, 443, 1024-65535.
• Instance port - The port that the ELB will use to send traffic to the application instances. Valid ports are 1 to 65535. The Instance Port does not have to match the Load Balancer Port.
• SSL Certificate (for HTTPS only) - Select the Server Certificate that will be used for (SSL) encryption purposes.

Sticky Session Policies tab

The Sticky Session Policies tab is where you can create a new Sticky Session policy for an AWS Elastic Load Balancer. By default, AWS ELB distributes requests to Instances running your application based on the lowest load. However, you can create a Sticky Session Policy so that a request is bound to the same Instance for the length of the entire session. Sticky sessions are based on either load balancer or application generated HTTP cookies.

Fields

• Policy Name - Enter the name of your Sticky Session Policy.
• Cookie Type - Select the type of cookie you want to use.
  • App Cookie - Allow the application to set the session lifetime.
  • Lb Cookie - Allow the Load Balancer (ELB) to set the session lifetime. If you specify Lb Cookie, you are prompted for a Cookie Expiration Period (in seconds). You cannot leave this field blank.
• Cookie Name - Enter the name of the Cookie.
• Listeners - A Sticky Session Policy can be associated with HTTP/HTTPS Listeners. Select one of the Listeners from the drop-down menu.

Servers tab

View a list of currently registered servers with the ELB. If you are expanding the ELB's serviceable availability zones you must first register instances in the new availability zone (us-east-1b), add them to the load balancer. Once the instances show up in the 'OutOfService' state for the LoadBalancer, you can finally edit the ELB and enable the new zone (us-east-1b).

Important! An ELB will round-robin traffic between all selected availability zones regardless of whether or not a serviceable instance exists in that zone. When creating an ELB, you must only select the availability zones in which instances are currently running and attached, otherwise a portion of your requests will return a 503 error.

Edit

You can edit the following variables for each elastic load balancer:

• Deployment - Select the deployment where the ELB will be used.
• Availability zones - Select which availability zones the load balancer will distribute traffic to. Select the availability zones that contains (or will contain) application servers that the ELB will send traffic to.
• Target - Specify the target port and protocol for the health check. Format is: Protocol (TCP or HTTP) and port (1 to 65535). Default is: TCP:80
• Interval - Health check interval. Approximate number of seconds between health checks of a given instance. Default is 30 seconds. (Must be between 5 and 600.)
• Timeout - Health check timeout. Number of seconds during which no response means a failed health check. Default is 5. (Must be between 2 and 60)
• Healthy threshold - Number of positive consecutive health checks before moving the instance back to the "Healthy" state. Default is 3. (Must be between 2 and 10)
• Unhealthy threshold - Number of negative consecutive health checks before moving the instance back to the "Unhealthy" state. Default is 5. (Must be between 2 and 10)